The present invention relates to solar screens, awnings, movie screens, roller shades and other sheet materials that are wound on roller tubes, and more particularly, to a roller tube including an integral slot that maintains a smooth outside diameter for attaching the sheet material. The resulting roller tube allows the sheet material to be wound therearound without any bumps or other imperfections.
Roller shade systems make use of flexible shades supported by elongated roller tubes. For purposes of the present disclosure, the term “shades” is intended to encompass any type of sheet material dispensed from a roller, including movie screens, solar shades, awnings, decorative shades, etc. The roller tube, typically made from polymer, plastic, aluminum or steel, is rotatably supported and provides support for the flexible shade on the roller tube. Roller shades include manual shades having spring driven roller tubes and motorized shades having drive motors engaging the roller tube to rotatingly drive the tube. The drive motors for motorized shades include externally mounted motors engaging an end of the roller tube (e.g., via gears and/or chains or belts) and internal motors that are received within an interior defined by the tube. Manual pull chain drives could alternatively be provided.
Conventional roller shades have support systems that engage the opposite ends of the roller tube to provide the rotatable support that is required for winding and unwinding of the flexible shade. The support system includes a drive end support assembly having a coupler engaging the open end of the tube for rotation. The coupler is adapted to receive the drive shaft of a motor such that rotation of the drive shaft is transferred to the coupler for rotation of the tube. The motor is secured to a bracket for attachment of the roller shade system to the wall or ceiling of a structure, for example. A coupler engaging an opposite end of the roller tube could receive a motor drive shaft or, alternatively, could receive a rotatably supported shaft of an idler assembly.
In certain roller tube arrangements, the drive motor is inserted into the roller tube body. The drive motor includes a substantially circular outer shape that snuggly fits into the inside diameter of the cylinder shaped roller tube.
The roller tube serves to support and fix the screen material, such that the screen can wind and unwind in a smooth manner. It is important in the attachment of the screen to the roller tube outside diameter to align the screen perpendicular to the axis of rotation of the roller tube. If the screen is out-of-square alignment with the roller tube, then the screen will wind and unwind in an uneven manner. A screen that is out of alignment can bind and create unsightly wrinkles along the surface of the solar screen/awning that is undesirable.
The prior art roller tube designs have attempted to solve the problem of attachment of the screen to the roller tube in various ways. A common prior art technique of attachment is to use double sided adhesive tape along the outer surface of the roller tube. The double sided tape adheres to both the roller tube and the screen. This tape technique can result in a time consuming process that can yield screens that are out of alignment. Moreover, the tape can result in a raised surface on the roller tube exterior surface, thereby creating a bump in the fabric or other material wound around the roller tube. Even an incongruity as small as one ten-thousandth of an inch can create a bump that results in a permanent deformity of the sheet material. Such a bump will result in unsightly horizontal lines and/or wrinkles when the material is unwound from the roller tube. Moreover, thicker sheet materials accentuate the bumps. Various tape thickness have been tried in order to blend the surface of the roller tube into the sheet material, but this has not been a satisfactory solution because it requires a very time consuming manufacturing process.
Another prior art technique of attachment is to form a groove in the roller tube exterior for insertion of the screen material. The groove acts to align the roller tube material sufficiently. This technique may include a separate bar that can clamp onto and or into the groove in the roller tube such that the screen material is clamped between the bar and the groove.
A substantial drawback of the prior art roller tube and groove techniques is that the groove formed in the roller tube creates a protrusion that bulges into the inside diameter of the roller tube. The protrusion into the prior art roller tubes inhibits the insertion of a drive motor into the roller tube. With the protrusion, the roller tube cannot accept the substantially circular drive motor without modification to the drive motor housing. Modification of the drive motor makes the installation more costly and less practical.
Other prior art attempts to maintain the circular inside diameter involve the use of additional clamping bars to the exterior of the roller tube. These techniques lose the advantage of the groove to provide a true orthogonal baseline to align the screen material, and create a bump in the material rolled around the tube.
It would be advantageous to provide a method and an apparatus to ensure that roller tube and screen material are in proper orthogonal alignment while being able to utilize interior drive motors without the added costs and complexity of the prior art systems. The present invention provides the aforementioned and other advantages.
What is needed in the art is a roller tube having an external slot for mounting the screen without forming protrusions in the roller tube interior or bumps in the material wound around the tube. It would be further advantageous to provide such roller tubes with a small diameter, and which will accommodate standard off the shelf motors that are readily available.